Background: Combination therapy with standard interferon (IFN) and ribavirin is more efficacious than IFN monotherapy1; however, whether PEG(40K)-IFN?-2a therapy will be enhanced in a similar manner in combination with ribavirin has not been established. Methods: Twenty patients with serologically and histologically established CHC received PEG(40K)-IFN?-2a (180 ?g SC qwk) plus oral ribavirin (1000-1200 mg BID) for 24 to 48 weeks (n=10, fasting; n=10, with meals). Treatment was followed by a 24-week treatment-free observation period. Genotype 1 patients who demonstrated evidence of response at Week 24 received extended treatment to 48 weeks. Genotype non-1 patients could receive extended treatment to Week 48 only at the discretion of the investigator and with approval of the sponsor. Patients were monitored for serum ALT and plasma HCV-RNA levels.